"Following Wednesday's injury, Radamel Falcao made a diagnostic examination. It appears that the player is suffering from trauma in the left knee with lesion of ligament anterior cruciate," AS Monaco said in a statement Thursday.

"The player will have surgery in next few days. Doctors will do everything possible to speed up recovery."

The impending surgery puts Falcao's participation in the World Cup in doubt.

Falcao admitted on Twitter on Thursday night that the injury was a devastating blow for him -- but at the same time he is not yet ready to accept his chances of making the finals are over completely.

He wrote in Spanish: "I want to thank all of you for so many messages of support in the last few hours, I'm really touched by the warmth that's been shown to me from all over the world.

"I'm not going to deny that my sadness is huge, my heart is broken, but I'm clinging to the smallest hope, and that's enough to think that my World Cup dream is still alive.

Falcao, 27, was carried off the pitch on a stretcher on Wednesday night following a heavy challenge by Soner Ertek in the 40th minute of Monaco's 3-0 Coupe de France win at Monts d'Or Azergues.

EFE reported that Jose Carlos Noronha, a specialist who treats Falcao, as telling it that the former Atletico Madrid forward has suffered damage to the anterior cruciate ligaments in his left knee and can expect to be out of action for six months.

"We are all very concerned over what happened with our star Falcao and we are vowing for his quick recovery," Jose Manuel Santos, President of Colombia, said from the World Economic Forum in Davos, Switzerland.

Falcao -- who scored nine goals in World Cup qualifying for Colombia -- is now set to travel to Oporto for further tests in order to discover the full extent of the injury.

Colombia international and Monaco teammate James Rodriguez offered his support, saying "Strength and faith, brother. We need you, football needs you."